If there is no pre-payment penalty on the car loan, I'd either try and pay it off quicker than the regular term (if it will save you interest).
Or I'd see what I could get with a smoking hot ad on craigslist....if you're funny/creative enough you can get it to go viral and sell that puppy asap. "This car was only driven by small green aliens from Alpha Centuri, and one distraught mother of an aged iguana who didn't like to travel. It will NEVER let you down! Had great tires, was never smoked in, and has never been used to transport live frogs."
(I'd also put in a 'straight' ad for it, stagger the ads so they're a few pages apart on "by owner only" section.)
The most difficult, time consuming, and chance-ridden option is to wait for the last day of the month (or preferably year) and swap it at a dealership LATE IN THE DAY.
They need to sell "one more car" to make the boss happy. If you are even a half assed negotiator you should be able to acquire something at an ok rate by waiting until they are under the gun to make a deal, versus you being under the gun.
The cheapest method of this is to open a few free email accounts FROM WORK (or the library) and do online queries at a few local places. Do NOT give your whole name OR phone number.
"I can't take calls at work and I am buying a car TOMORROW, someplace. I need your "OUT THE DOOR, ALL IN" price on stock #1234. Run your 4-square, talk to your manager, do whatever: but I am buying a car. And I have a xxx trade in with xxx miles on it."
If you call them they will pull your # from caller ID, or if you email them from your home computer they will hound you for the rest of your life. Seriously: like, ten years later you'll get bullshit emails. So use a faux account and don't call---and call from work or pay phone--- until the "is this vehicle you emailed me about still on the lot? What is your best price OTD today?"
Good luck.